Are you using the PTFE tube? I have seen it both ways, not to hard to try it both ways as well just curious about users experience either way.

Where are you connecting the fan to your RAMPS, RUMBA or RAMBO? Just using the normal 12V out (D9 on RAMPS) so that it is on all the time? Also was the fan sufficent in keeping the cool end of the hot end cool for PLA?

Have you tried fitting another fan to cool the print or is the downward draft from the extruder fan enough?
I have the Bulldog Lite driving an E3Dv6 1.75. I do use the PTFE tube. I didn't at first, but I believe that it is running better with it installed.

I am not using the fan base that came with the Bulldog. I installed the Bulldog on a custom carrier. You do have to run the fan on the E3D all the time, so it is plugged in accordingly. In fact, the E3D is so cool above the heat break that you can leave your finger on it. It the E3D fan fails, that falls apart quickly with a jamb sure to follow. You have to be careful with that little fan as it is easy to break.

I do run two fans to cool my prints. I am running PLA. My custom carrier has mounts for two fans (one on each side of the extruder) which I generally turn on when the second layer starts. Although it varies a bit depending on the PLA or part, I am running the E3D at about 210C and I run the print bed at 75C sometimes going to 70C with the second layer.

I am currently finishing up the build on a Makerfarm using a Bulldog XL with a 3mm E3Dv6. This has been a slow build as I am trying to make it really nice, using ideas from some others and a few of my own. It has also been slow because life has been getting in the way. I purchased all the parts in November last year.

The custom carriage I designed provides a mount for the Bulldog Lite, allows for mounting an ABL servo and the two print cooling fans. I have not tried the ABL, but intend to when I rebuild that printer. (The plan is to rebuild the first printer once the second one is up and running efficiently). The final design is still in flux, for both the Lite and XL, but I have been using the prototype carriage with the Bulldog Lite and E3D for about 8 months now.

So far, I am very happy with the combination (Bulldog and E3Dv6).